System and method for minimally invasive cutting instrument operation

This patent application is a continuation of U.S. patent application Ser. No. 17/102,210 (filed Nov. 23, 2020), which is divisional of U.S. patent application Ser. No. 15/573,096 (filed on Nov. 9, 2017), which is a U.S. National Stage patent application of International Patent Application No. PCT/US2016/032351 (filed on May 13, 2016), the benefit of which is claimed, and claims priority to and the benefit of the filing date of U.S. Provisional Patent Application 62/162,217, entitled “SYSTEM AND METHOD FOR MINIMALLY INVASIVE CUTTING INSTRUMENT OPERATION” and filed May 15, 2015, each of which is incorporated by reference herein in its entirety.

The present disclosure relates generally to operation of devices with articulated arms and end effectors and more particularly to operation of a minimally invasive cutting instrument.

More and more devices are being replaced with autonomous and semiautonomous electronic devices. This is especially true in the hospitals of today with large arrays of autonomous and semiautonomous electronic devices being found in operating rooms, interventional suites, intensive care wards, emergency rooms, and the like. For example, glass and mercury thermometers are being replaced with electronic thermometers, intravenous drip lines now include electronic monitors and flow regulators, and traditional hand-held surgical instruments are being replaced by computer-assisted medical devices.

Minimally invasive surgical techniques using computer-assisted medical devices generally attempt to perform surgical and/or other procedures while minimizing damage to healthy tissue. Some minimally invasive procedures may be performed remotely through the use of computer-assisted medical devices with surgical instruments. With many computer-assisted medical devices, a surgeon and/or other medical personnel may typically manipulate input devices using one or more controls on an operator console. As the surgeon and/or other medical personnel operate the various controls at the operator console, the commands are relayed from the operator console to a patient side device to which one or more end effectors and/or surgical instruments are mounted. In this way, the surgeon and/or other medical personnel are able to perform one or more procedures on a patient using the end effectors and/or surgical instruments. Depending upon the desired procedure and/or the surgical instruments in use, the desired procedure may be performed partially or wholly under control of the surgeon and/or medical personnel using teleoperation and/or under semi-autonomous control where the surgical instrument may perform a sequence of operations based on one or more activation actions by the surgeon and/or other medical personnel.

Minimally invasive surgical instruments, whether actuated manually, teleoperatively, and/or semi-autonomously may be used in a variety of operations and/or procedures and may have various configurations. Many such instruments include an end effector mounted at a distal end of a shaft that may be mounted to the distal end of an articulated arm. In many operational scenarios, the shaft may be configured to be inserted (e.g., laparoscopically, thoracoscopically, and/or the like) through an opening (e.g., a body wall incision, a natural orifice, and/or the like) to reach a remote surgical site. In some instruments, an articulating wrist mechanism may be mounted to the distal end of the instrument's shaft to support the end effector with the articulating wrist providing the ability to alter an orientation of the end effector relative to a longitudinal axis of the shaft.

End effectors of different design and/or configuration may be used to perform different tasks, procedures, and functions so as to be allow the surgeon and/or other medical personnel to perform any of a variety of surgical procedures. Examples include, but are not limited to, cauterizing, ablating, suturing, cutting, stapling, fusing, sealing, etc., and/or combinations thereof. Accordingly, end effectors can include a variety of components and/or combinations of components to perform these surgical procedures.

Consistent with the goals of a minimally invasive procedure, the size of the end effector is typically kept as small as possible while still allowing it to perform its intended task. One approach to keeping the size of the end effector small is to accomplish actuation of the end effector through the use of one or more inputs at a proximal end of the surgical instrument, which is typically located externally to the patient. Various gears, levers, pulleys, cables, rods, bands, and/or the like, may then be used to transmit actions from the one or more inputs along the shaft of the surgical instrument and to actuate the end effector. In the case of a computer-assisted medical device with an appropriate surgical instrument, a transmission mechanism at the proximal end of the instrument interfaces with various motors, solenoids, servos, active actuators, hydraulics, pneumatics, and/or the like provided on an articulated arm of the patient side device or a patient side cart. The motors, solenoids, servos, active actuators, hydraulics, pneumatics, and/or the like typically receive control signals through a master controller and provide input in the form of force and/or torque at the proximal end of the transmission mechanism, which the various gears, levers, pulleys, cables, rods, bands, and/or the like ultimately transmit to actuate the end effector at the distal end of the transmission mechanism.

Because of the remote nature of the operation of such end effectors, it may be difficult in some cases for the surgeon and/or other medical personnel to know the position of one or more components of the end effector during actuation to perform a desired procedure. For example, in some cases, other portions of the surgical instrument, including the end effector itself, and/or parts of the anatomy of the patient may hide from view one or more components of the surgical instrument during the actuation of the one or more components. Additionally, when one or more of the components encounters a fault condition while attempting to perform the desired procedure, it may be difficult for the surgeon and/or other medical personnel to detect and/or correct the fault condition due to the limited visibility of the end effector, the limited space in which the surgical instrument operates, the limited access to the surgical instrument, the remote position of the end effector relative to the surgeon and/or other medical personnel, and/or the like.

In addition, safety conditions may also be a factor in the design and/or operation of the surgical instrument. In some examples, the end effector of a surgical tool, such as a cutting tool, may include a sharp cutting blade. When the cutting blade is not actively being used to cut, the cutting blade may be sheathed and/or garaged within a housing on the end effector so that it is generally positioned where it cannot accidentally cut tissue of the patient and/or medical personnel manipulating the surgical tool during non-operation. Similarly, one or more delicate components of the end effector may also be sheathed and/or garaged to prevent damage to the delicate components during non-operation.

Accordingly, improved methods and systems for the operation of surgical instruments, such as a cutting instrument, are desirable. In some examples, it may be desirable to provide automated control of the surgical instrument so as to help ensure that the surgical instrument may be able to successfully perform a desired procedure. In some examples, it may be desirable to provide a configuration of the surgical instrument that supports safety to the patient and/or medical personnel and protection to the surgical instrument during both operation and non-operation.

Consistent with some embodiments, a surgical cutting instrument for use with a computer-assisted medical device. The surgical cutting instrument includes a drive unit, an end effector located at a distal end of the instrument, a shaft between the drive unit and the end effector, and a garage for housing the cutting blade when the cutting blade is not in use. The end effector includes opposable gripping jaws and a cutting blade. The shaft houses one or more drive mechanisms for coupling force or torque from the drive unit to the end effector. To perform a cutting operation, the instrument is configured to extend the cutting blade from a first position to a second position, retract the cutting blade from the second position to a third position between the first and second positions, and further retract the cutting blade to the first position. While the cutting blade is not in use, the cutting blade is maintained in the first position using a restraining mechanism in the drive unit, force or torque applied by a motor or other active actuator to the drive unit, or both.

Consistent with some embodiments, a method of performing a cutting operation using a surgical cutting instrument for use with a computer-assisted medical device includes holding a cutting blade of an end effector in a first position when the cutting blade is not in use, extending the cutting blade from the first position to a second position by applying force or torque to the drive unit, retracting the cutting blade from the second position to a third position between the first and second positions, and further retracting the cutting blade to the first position. The holding of the cutting blade in the first position is performed by a restraining mechanism of a drive unit, a force or torque applied to the drive unit by a motor or active actuator, or both. The extending and retracting comprise applying force or torque to the drive unit using the motor or active actuator.

Consistent with some embodiments, a non-transitory machine-readable medium includes a plurality of machine-readable instructions which when executed by one or more processors associated with a computer-assisted medical device are adapted to cause the one or more processors to perform a method. The method includes holding a cutting blade of an end effector in a first position when the cutting blade is not in use, extending the cutting blade from the first position to a second position by applying force or torque to the drive unit, retracting the cutting blade from the second position to a third position between the first and second positions, and further retracting the cutting blade to the first position. The holding the cutting blade in the first position is performed by a restraining mechanism of a drive unit, a force or torque applied to the drive unit by a motor or active actuator, or both. The extending and retracting includes applying force or torque to the drive unit using the motor or active actuator.

Consistent with some embodiments, a computer-assisted medical device includes one or more processors, an articulated arm, a motor or other active actuator, and a surgical instrument coupled to a distal end of the articulated arm. The surgical instrument includes a drive unit located at a proximal end of the surgical instrument, an end effector located at a distal end of the surgical instrument, a shaft between the drive unit and the end effector, and a garage for housing the cutting blade when the cutting blade is not in use. The end effector comprising opposable gripping jaws and a cutting blade. The shaft houses one or more drive mechanisms for coupling force or torque from the drive unit to the end effector. The computer-assisted medical device is configured to perform a cutting operation using the cutting blade by extending the cutting blade from a first position to a second position, retracting the cutting blade from the second position to a third position between the first and second positions, and further retracting the cutting blade to the first position. While the cutting blade is not in use, the cutting blade is maintained in the first position using a restraining mechanism in the drive unit, force or torque applied by the motor or other active actuator to the drive unit, or both.

In the figures, elements having the same designations have the same or similar functions.

In the following description, specific details are set forth describing some embodiments consistent with the present disclosure. It will be apparent to one skilled in the art, however, that some embodiments may be practiced without some or all of these specific details. The specific embodiments disclosed herein are meant to be illustrative but not limiting. One skilled in the art may realize other elements that, although not specifically described here, are within the scope and the spirit of this disclosure. In addition, to avoid unnecessary repetition, one or more features shown and described in association with one embodiment may be incorporated into other embodiments unless specifically described otherwise or if the one or more features would make an embodiment non-functional.

is a simplified diagram of a computer-assisted systemaccording to some embodiments. As shown in, computer-assisted systemincludes a computer-assisted devicewith one or more movable or articulated arms. Each of the one or more articulated armsmay support one or more instruments. In some examples, computer-assisted devicemay be consistent with a computer-assisted surgical device. The one or more articulated armsmay each provide support for medical instrumentssuch as surgical instruments, imaging devices, and/or the like. In some examples, the instrumentsmay include end effectors that are capable of, but are not limited to, performing, gripping, retracting, cauterizing, ablating, suturing, cutting, stapling, fusing, sealing, etc., and/or combinations thereof.

Computer-assisted devicemay further be coupled to an operator workstation (not shown), which may include one or more master controls for operating the computer-assisted device, the one or more articulated arms, and/or the instruments. In some examples, the one or more master controls may include master manipulators, levers, pedals, switches, keys, knobs, triggers, and/or the like. In some embodiments, computer-assisted deviceand the operator workstation may correspond to a da Vinci® Surgical System commercialized by Intuitive Surgical, Inc. of Sunnyvale, California. In some embodiments, computer-assisted surgical devices with other configurations, fewer or more articulated arms, and/or the like may be used with computer-assisted system.

Computer-assisted deviceis coupled to a control unitvia an interface. The interface may include one or more cables, fibers, connectors, and/or buses and may further include one or more networks with one or more network switching and/or routing devices. Control unitincludes a processorcoupled to memory. Operation of control unitis controlled by processor. And although control unitis shown with only one processor, it is understood that processormay be representative of one or more central processing units, multi-core processors, microprocessors, microcontrollers, digital signal processors, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), and/or the like in control unit. Control unitmay be implemented as a stand-alone subsystem and/or board added to a computing device or as a virtual machine. In some embodiments, control unitmay be included as part of the operator workstation and/or operated separately from, but in coordination with the operator workstation.

Memorymay be used to store software executed by control unitand/or one or more data structures used during operation of control unit. Memorymay include one or more types of machine readable media. Some common forms of machine readable media may include floppy disk, flexible disk, hard disk, magnetic tape, any other magnetic medium, CD-ROM, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, RAM, PROM, EPROM, FLASH-EPROM, any other memory chip or cartridge, and/or any other medium from which a processor or computer is adapted to read.

As shown in, memoryincludes a control applicationthat may be used to support autonomous, semiautonomous, and/or teleoperated control of computer-assisted device. Control applicationmay include one or more application programming interfaces (APIs) for receiving position, motion, force, torque, and/or other sensor information from computer-assisted device, articulated arms, and/or instruments, exchanging position, motion, force, torque, and/or collision avoidance information with other control units regarding other devices, and/or planning and/or assisting in the planning of motion for computer-assisted device, articulated arms, and/or instruments. In some examples, control applicationmay further support autonomous, semiautonomous, and/or teleoperated control of the instrumentsduring a surgical procedure. And although control applicationis depicted as a software application, control applicationmay be implemented using hardware, software, and/or a combination of hardware and software.

In some embodiments, computer-assisted systemmay be found in an operating room and/or an interventional suite. And although computer-assisted systemincludes only one computer-assisted devicewith two articulated armsand corresponding instruments, one of ordinary skill would understand that computer-assisted systemmay include any number of computer-assisted devices with articulated arms and/or instruments of similar and/or different in design from computer-assisted device. In some examples, each of the computer-assisted devices may include fewer or more articulated arms and/or instruments.

is a simplified diagram showing a minimally invasive surgical instrumentaccording to some embodiments. In some embodiments, surgical instrumentmay be consistent with any of the instrumentsof. The directions “proximal” and “distal” as depicted inand as used herein help describe the relative orientation and location of components of surgical instrument. Distal generally refers to elements in a direction further along a kinematic chain from a base of a computer-assisted device, such as computer-assisted device, and/or or closest to the surgical work site in the intended operational use of the surgical instrument. Proximal generally refers to elements in a direction closer along a kinematic chain toward the base of the computer-assisted device and/or one of the articulated arms of the computer-assisted device.

As shown in, surgical instrumentincludes a long shaftused to couple an end effectorlocated at a distal end of shaftto where the surgical instrumentis mounted to an articulated arm and/or a computer-assisted device at a proximal end of shaft. Depending upon the particular procedure for which the surgical instrumentis being used, shaftmay be inserted through an opening (e.g., a body wall incision, a natural orifice, and/or the like) in order to place end effectorin proximity to a remote surgical site located within the anatomy of a patient. As further shown in, end effectoris generally consistent with a two-jawed gripper-style end effector, which in some embodiments may further include a cutting and/or a fusing or sealing mechanism as is described in further detail below with respect to. However, one of ordinary skill would understand that different surgical instrumentswith different end effectorsare possible and may be consistent with the embodiments of surgical instrumentas described elsewhere herein.

A surgical instrument, such as surgical instrumentwith end effectortypically relies on multiple degrees of freedom (DOFs) during its operation. Depending upon the configuration of surgical instrumentand the articulated arm and/or computer-assisted device to which it is mounted, various DOFs that may be used to position, orient, and/or operate end effectorare possible. In some examples, shaftmay be inserted in a distal direction and/or retreated in a proximal direction to provide an insertion DOF that may be used to control how deep within the anatomy of the patient that end effectoris placed. In some examples, shaftmay be able rotate about its longitudinal axis to provide a roll DOF that may be used to rotate end effector. In some examples, additional flexibility in the position and/or orientation of end effectormay be provided by an articulated wristthat is used to couple end effectorto the distal end of shaft. In some examples, articulated wristmay include one or more rotational joints, such as one or more roll, pitch or yaw joints that may provide one or more “roll,” “pitch,” and “yaw” DOF(s), respectively, that may be used to control an orientation of end effectorrelative to the longitudinal axis of shaft. In some examples, the one or more rotational joints may include a pitch and a yaw joint; a roll, a pitch, and a yaw joint, a roll, a pitch, and a roll joint; and/or the like. In some examples, end effectormay further include a grip DOF used to control the opening and closing of the jaws of end effectorand/or an activation DOF used to control the extension, retraction, and/or operation of a cutting mechanism as is described in further detail below.

Surgical instrumentfurther includes a drive systemlocated at the proximal end of shaft. Drive systemincludes one or more components for introducing forces and/or torques to surgical instrumentthat may be used to manipulate the various DOFs supported by surgical instrument. In some examples, drive systemmay include one or more motors, solenoids, servos, active actuators, hydraulic actuators, pneumatic actuators, and/or the like that are operated based on signals received from a control unit, such as control unitof. In some examples, the signals may include one or more currents, voltages, pulse-width modulated wave forms, and/or the like. In some examples, drive systemmay include one or more shafts, gears, pulleys, rods, bands, and/or the like which may be coupled to corresponding motors, solenoids, servos, active actuators, hydraulics, pneumatics, and/or the like that are part of the articulated arm, such as any of the articulated arms, to which surgical instrumentis mounted. In some examples, the one or more drive inputs, such as shafts, gears, pulleys, rods, bands, and/or the like, may be used to receive forces and/or torques from the motors, solenoids, servos, active actuators, hydraulics, pneumatics, and/or the like and apply those forces and/or torques to adjust the various DOFs of surgical instrument.

In some embodiments, the forces and/or torques generated by and/or received by drive systemmay be transferred from drive systemand along shaftto the various joints and/or elements of surgical instrumentlocated distal to drive systemusing one or more drive mechanisms. In some examples, the one or more drive mechanismsmay include one or more gears, levers, pulleys, cables, rods, bands, and/or the like. In some examples, shaftis hollow and the drive mechanismspass along the inside of shaftfrom drive systemto the corresponding DOF in end effectorand/or articulated wrist. In some examples, each of the drive mechanismsmay be a cable disposed inside a hollow sheath or lumen in a Bowden cable like configuration. In some examples, the cable and/or the inside of the lumen may be coated with a low-friction coating such as polytetrafluoroethylene (PTFE) and/or the like. In some examples, as the proximal end of each of the cables is pulled and/or pushed inside drive system, such as by wrapping and/or unwrapping the cable about a capstan or shaft, the distal end of the cable moves accordingly and applies a suitable force and/or torque to adjust one of the DOFs of end effector, articulated wrist, and/or surgical instrument.

is a simplified perspective diagram of the distal end of surgical instrumentaccording to some embodiments. As shown in, the distal end of surgical instrumentis depicted so as to show additional details of end effector, articulated wrist, and drive mechanisms. In more detail, end effectorincludes opposing jawsshown in an open position. Jawsare configured to move between open and closed positions so that end effectormay be used during a procedure to grip and release tissue and/or other structures, such as sutures, located at the surgical site. In some examples, jawsmay be operated together as a single unit with both jawsopening and/or closing at the same time. In some examples, jawsmay be opened and/or closed independently so that, for example, one jawcould be held steady which the other jawmay be opened and/or closed.

shows that a gripping surface on an inside of each of jawsincludes a corresponding groove, which may act as a guide for a cutting blade, although the groovemay be omitted from one or more of jaws. As cutting bladeis extended toward the distal end of end effectorand/or retracted toward the proximal end of end effector, each of the groovesmay aid in the alignment and/or positioning of cutting bladeduring a cutting operation. Extraction and/or retraction of cutting bladeis accomplished using a drive componentto which cutting bladeis attached. In some examples, drive componentpushes on cutting bladeto extend cutting bladeand pulls on cutting bladeto retract cutting blade. Use and positioning of cutting bladeis shown in, which are simplified cut-away diagrams of end effectoraccording to some embodiments.shows the relationship between cutting bladeand drive component.

End effectorfurther includes a garage featurelocated at a proximal end of jaws. Garage featureincludes an opening through which both drive componentand cutting blademay pass. Garage featureis configured to provide a safe storage area for cutting bladewhen cutting bladeis not in use. Thus, when cutting bladeis not actively being used as part of a cutting operation, end effectoris configured so that cutting blademay be retracted into garage featurein a “garaged” or stored position in which cutting bladeis recessed proximally behind jawsas shown in. Cutting blademay additionally be extended to a position in which cutting bladeis positioned at or near a distal end of one of the groovesas shown in. In some examples, the positioning of cutting bladeas shown inmay correspond to a position of cutting bladeduring a cutting operation.

In some examples, end effectorand surgical instrumentare designed so that the default or home position of cutting bladeis within garage feature. This arrangement of garage featuremay provide several features to end effector. In some examples, when cutting bladeis retracted into garage feature, the sharp cutting edge of cutting bladeis effectively sheathed so that cutting bladeis unlikely to accidentally cut tissue during a procedure and/or medical personnel handling surgical instrumentand/or end effectorbefore and/or after a procedure. In some examples, when cutting bladeis retracted into garage feature, cutting blademay also be protected from damage, such as accidental dulling, when cutting bladeis not actively being used to cut.

Referring back to, in some embodiments, the gripping surface on the inside of each of jawsmay further include one or more optional electrodes. In some examples, electrodesmay be used to deliver electrosurgical energy to fuse tissue being held between jaws. In some examples, electrodesmay provide an electro-cautery, fusing, and/or sealing feature to end effectorso that tissue may be cut and/or fused/sealed using the same surgical tool.

In some embodiments, operation of jaws, cutting blade, and/or the joints of articulated wristmay be accomplished using corresponding ones of the drive mechanisms. In some examples, when jawsare operated independently, a distal end of two of the drive mechanisms(one for each of jaws) may be coupled to a respective jawso that as the corresponding drive mechanismapplies a pull and/or a pushing force (for example, using a cable, lead screw, and/or the like), the respective jawmay be opened and/or closed. In some examples, when jawsare operated together, both jawsmay be coupled to the distal end of the same drive mechanism. In some examples, drive componentmay be coupled to a distal end of a corresponding drive mechanismso that forces and/or torques applied to the corresponding drive mechanismmay be transferred to the push and/or pull motion of drive component. In some examples, additional drive mechanismsmay be used to operate the roll, pitch, and/or yaw DOFs in articulated wrist.

is a simplified perspective diagram of a drive unitfor a degree of freedom according to some embodiments. According to some embodiments, drive unitmay be representative of a portion of the components in drive systemof. As shown in, drive unitis based on a rotational actuation approach in which a capstanis rotated to actuate a DOF. Capstanis coupled to a drive shaftwhich may be the drive shaft of a motor, servo, active actuator, hydraulic actuator, pneumatic actuator, and/or the like (not shown). As torque is applied to drive shaftand drive shaftand capstanare rotated, a cableattached to capstanand/or drive shaftmay be further wrapped around and/or unwrapped from around capstanand/or drive shaft. When cableis attached to the proximal end of a corresponding drive mechanism, such as any of drive mechanisms, the wrapping and unwrapping of the cable may translate into corresponding pulling and pushing forces and/or torques that may be applied to a DOF of an end effector located at the distal end of the drive mechanism. In some examples, rotation of capstanand drive shaftand the corresponding wrapping and/or unwrapping of cablemay result in opening and/or closing of gripper jaws such as jaws, extending and/or retracting of a cutting blade such as cutting blade, flexing and/or unflexing of articulated wrist joints, and/or the like. In some examples, monitoring a rotation angle and/or rotational velocity of capstanand/or drive shaftmay also provide an indication of a current position and/or velocity of the corresponding DOF coupled to cablethrough the corresponding drive mechanism. Thus, when drive unitis used in conjunction with the DOFs of surgical instrument, the rotation angle and/or rotational velocity of capstanand/or drive shaftmay provide useful feedback on the angle to which jawsare opened, the position of cutting blade, and/or the pitch and/or yaw angle of articulated wristdepending on which of the drive mechanismscableis coupled.

Because it is often desirable for a DOF in an end effector to be configured with a default, rest, and/or home position when the DOF is not being actuated, in some embodiments a drive unit, such as drive unitmay include some type of resistive and/or restraining mechanism to return drive unitto a corresponding home position. In some examples, use of a home position for a DOF may support configuration of a surgical instrument, such as surgical instrument, where gripping jaws are automatically closed and/or mostly closed, cutting blades are retracted into a garage feature, articulated wrist joints are straightened, and/or the like. As shown in, drive unitincludes a restraining mechanism in the form of a torsion spring. Torsion springis shown attached at one endto capstanand wrapped around capstan. As capstanis rotated, a second endof torsion springmay freely rotate until it rotates up against a stopthat may be part of a body of drive unit. As capstancontinues to rotate after the second endof torsion springis against stop, torsion springwill begin to provide a restraining and/or return to home force and/or torque to capstanas dictated by the amount of rotation of capstanand a spring constant of torsion spring. Thus, as greater amounts of rotation are applied to capstan, torsion springapplies increasing return to home force and/or torque to capstan. It is this return to home force and/or torque on capstanthat may be used, for example, to close the gripping jaws, retract the cutting blade, and/or straighten the articulated wrist joints.

Althoughshows the restraining mechanism as a torsion spring wrapped around capstan, one of ordinary skill would recognize other possible restraining mechanisms and/or configurations for the restraining mechanisms to accomplish a similar restraining/return to home function. In some examples, the body of drive unitmay further include a second stop to provide a return to home force and/or torque to capstanin an opposite direction to the return to home force and/or torque resulting from stop. In some examples, the second endof torsion springmay be mounted to the body of drive unitso that no free movement of torsion springis permitted before torsion springbegins applying return to home force and/or torque to capstanand/or torsion springapplies at least some return to home force and/or torque to capstaneven without rotation of capstan.

According to some embodiments, selection of an appropriately sized restraining mechanism, such as the spring constant for torsion spring, for a DOF of an end effector may present several challenges to the designer of a surgical instrument. In some situations it may be desirable to select the size of the restraining mechanism to overcome any likely and/or reasonable interference with the desired return to home function of the corresponding drive unit of the DOF. In some examples, selection of the size of the restraining mechanism to overcome any likely and/or reasonable interference tends to oversize the restraining mechanism for many of the possible operational scenarios. Additionally, as the size of the restraining mechanism increases, a corresponding greater force or torque has to be applied to the drive unit to overcome the restraining mechanism. In some examples, this may include the use of a larger motor, solenoid, servo, active actuator, hydraulic actuator, pneumatic actuator, and/or the like to overcome the restraining mechanism or result in a smaller operational margin for the DOF that results in less force and/or torque being available to drive the DOF to perform an operation. For example, less cutting force and/or torque may be available to apply to a cutting blade to perform a cut. In some examples, this larger return to home force and/or torque may increase the stress and/or strain placed on the drive mechanism that may result in increased wear on the drive mechanism, stretching of the drive mechanism, and/or the like. In some examples, the stretching of the drive mechanism may result in the drive mechanism and the corresponding DOF becoming out of tolerance, thus resulting is a diminished ability to control the DOF as desired. In some examples, this larger return to home force and/or torque may increase the likelihood of injury to a patient and/or medical personnel, such as when a return to home gripping force may result in damage and/or tearing of tissue still located between the gripping jaws of an end effector.

One possible compromise is to size the restraining mechanism to provide sufficient return to home force and/or torque to return the DOF to the home position when the surgical instrument is not being used (i.e., when the surgical instrument is not mounted to a corresponding articulated arm and/or computer-assisted device) and to use the motor, solenoid, servo, active actuator, hydraulic actuator, pneumatic actuator, and/or the like coupled to the drive unit to provide additional return to home force and/or torque during operational scenarios where additional return to home force and/or torque is desired. Under this compromise, it is generally possible to use smaller motors, solenoids, servos, active actuators, hydraulic actuators, pneumatic actuators, and/or the like while still providing a desired amount of operational margin to support the desired operations of the corresponding surgical instrument. In some examples, the restraining mechanism may be sized to provide approximately 0 N to 10 N of return to home force and/or a similar torque to the DOF.

is a simplified diagram of a positional profileand a corresponding torque limit profilefor a cutting operation according to some embodiments. In some embodiments, positional profileand torque limit profilemay be suitable for application to cutting bladeusing drive unit. As shown in, positional profileand torque limit profileinclude a four-phase cutting operation beginning at a time to. The four phases include an extending phase from tto t, a holding phase from tto t, a retracting phase from tto t, and a garaging phase from tto t. For the purposes of discussing, the position of the cutting blade will be described relative to an x position of the cutting blade with more positive positions being in a distal direction, however, one of ordinary skill would understand that the positions for the cutting blade may be represented using any suitable positional and/or rotational axis such as a position along an axis defined by groove, a rotational angle of capstan, and/or the like and/or could alternatively be characterized with positive values in a more proximal direction.

One of the goals of the extending phase is to rapidly extend the cutting blade from a retracted position of xto an extended position of x. In some examples, xmay correspond to a garaged and/or home position of the cutting blade. In some examples, the zero position for the cutting blade may correspond to an outer or distal edge of a garage feature, such as garage feature, when the articulated wrist is in a straight or unflexed position. In some examples, xis selected as a sufficiently negative value, such as approximately −3 mm, to account for variability among different drive mechanisms and/or drive units. In some examples, a negative xmay also address possible deviations in the drive mechanism caused by the flexing of the articulated wrist in the surgical instrument. In some examples, as the articulated wrist flexes, the drive mechanism may be subject to bending and/or movement within the hollow shaft (e.g., shaft) of the surgical instrument. As the drive mechanism bends and/or moves an effective distance, as seen by the drive mechanism, may change between the distal end at the cutting blade and the proximal end at the drive unit. As a result, the amount of retraction to return the cutting blade to the garage may vary between situations where the articulated wrist is flexed and unflexed. In some examples, xmay correspond to a fully and/or mostly extended position for the cutting blade, such as approximately +18 mm, so that the cutting blade does not strike the end of a guiding groove, such as one of the grooves, and/or to reduce the likelihood of cutting blade exposure where the cutting blade comes out of the guiding grooves and is not able to be retracted back into the garaged or home position. In some examples, a duration of the extending phase (i.e., the time between tand t) may be rather rapid and may vary, for example, from 50 ms to 250 ms in length, and preferably 175 ms in length.

One of the goals of the holding phase is to continue to command the cutting blade to full extension at xto account for operational scenarios when it takes longer than the duration of the extending phase for the cutting blade to transition from xto x. In some examples, the holding phase may also reduce the likelihood that the cutting blade will be retracted before it has reached the desired extension. In some examples, a duration of the holding phase (i.e., the time between tand t) may be similar in magnitude to the duration of the extending phase or slightly shorter and may vary, for example, from 50 ms to 150 ms in length, and preferably 100 ms in length.

Retraction of the cutting blade may occur using a two-phase operation that includes the retracting phase and the garaging phase. One of the goals of the retracting phase is to rapidly retract the cutting blade to a position xthat corresponds to retracting the cutting blade to a hold position that is most of the way back to the garaged or home position, such as approximately +1 mm. Following the retracting phase, the cutting blade is more completely retracted to the xposition during the garaging phase. In some examples, the use of the two-phase operation of retracting followed by garaging may reduce the likelihood that the cutting blade may rebound back out the garage during retraction relative to a single-phase operation directly to xand/or reduce the magnitude of loads applied to the cutting blade and drive mechanism during the garaging phase. In some examples, a duration of the retracting phase (i.e., the time between tand t) may vary, for example, from 50 ms to 175 ms in length, and preferably 120 ms in length. In some examples, a duration of the garaging phase (i.e., the time between tand t) may vary, for example, from 75 ms to 200 ms in length, and preferably 150 ms in length.

In some examples, the time periods before to, when the cutting operation begins, and after t, when the cutting operation ends, may correspond to idle phases where the cutting blade is held at the garaged or home position of xusing force and/or torque provided by both the restraining mechanism of the drive unit and the motor, solenoid, servo, active actuator, hydraulic actuator, pneumatic actuator, and/or the like used to operate the drive unit as is discussed further below.

According to some embodiments, the positional profileofrepresents a desired position of the cutting blade during a cutting operation. In some examples, positional profilemay be converted to a time sequence of position commands for the cutting blade and the motor, solenoid, server actuator, hydraulic actuator, pneumatic actuator, and/or the like used to actuate the drive unit for the cutting blade. In some examples, interpolation and/or curve fitting using, for example, a cubic spline may be used to determine the time sequence of position commands so as to provide a smooth positional profileor position trajectory for the cutting blade throughout the cutting operation. In some examples, the actual position of the cutting blade and/or the drive unit may be monitored during the cutting operation using one or more sensors to determine whether the cutting blade and/or the drive unit are able to follow the positional profile. In some examples, when the cutting blade and/or the drive unit are not able to follow the positional profilewithin a predefined tolerance, an audio, visual, and/or textual alert may be provided to the surgeon and/or other medical personnel to indicate that the cutting operation may not have been successful. In some examples, the cutting operation may not be successful when the cutting blade is not able to extend to xand/or becomes exposed and cannot return to x.

According to some embodiments, even though the cutting blade is generally operated using a position control approach as indicated by positional profile, the control unit for the motor, solenoid, servo, active actuator, hydraulic actuator, pneumatic actuator, and/or the like driving the drive unit for the cutting blade may be subject to upper and/or lower force and/or torque limits. In some examples, the force and/or torque limits may be determined based on the size of the motor, solenoid, servo, active actuator, hydraulic actuator, pneumatic actuator, and/or the like, to reduce the likelihood of damage and/or excessive wear to the drive unit, drive mechanism, and/or cutting blade, to reduce power used to actuate the cutting blade, and/or to address the practical needs of the cutting operation. Torque limit profilerepresents one possible such profile and, although torque limit profileis described in terms of torques, other control actuators and/or control systems may alternatively use limits to voltage, current, force, duty cycle, and/or the like as would be understood by one of ordinary skill in the art.

As shown in, torque limit profileuses a combination of three torque limits depending upon which phase of the cutting operation the cutting blade is in and/or whether the cutting blade is currently idle. And although the torque limits are characterized with a positive torque limit value corresponding to an extending direction, one of ordinary skill would understand that the sign of the torque limit is arbitrary depending on the configuration of the control actuators and/or the drive unit for the cutting blade. In torque limit profile, a torque limit of TEXT is used during the extending and holding phases of the cutting operation. In some examples, TEXT is set at a sufficiently high limit to overcome any restraining mechanism, such as torsion spring, in the drive unit and to supply suitable actuating force and/or torque to allow the cutting blade to cut tissue while the cutting blade is being extended. In some examples, TEXT may be in a range suitable for the cutting blade to deliver 15 N to 20 N of cutting force during extension.

A torque limit of Tis used during the retracting and garaging phases. In some examples, Tis set at a sufficiently high limit to overcome any tissue and/or other debris from the cutting operation that may interfere with the desired retraction and/or garaging of the cutting blade after cutting has taken place. In some examples, Tmay have approximately the same magnitude as TEXT, but with an opposite sign so that Tmay be in a range suitable for delivering 15 N to 20 N of retracting force to the cutting blade. In some examples, Tmay have a magnitude smaller than that of TEXT to account for the torque used to overcome the restraining mechanism during extension and to reflect the assistance provided by the restraining mechanism during retraction.

A torque limit of Tis used when the cutting blade is idle. In some examples, Tis set to a lower magnitude than T, but with a magnitude sufficient to assist the restraining mechanism in keeping the cutting blade garaged during periods of non-use. In some examples, the magnitude of TIME may be set to avoid placing excessive strain on the motor, solenoid, servo, active actuator, hydraulic actuator, pneumatic actuator, drive mechanism, drive, unit, etc. due to attempts to retract the cutting blade beyond any physical limits imposed by the end effector and/or garage feature due to the negative retraction position of x. In some examples, Tmay be in a range suitable for delivering 0 N to 5 N of retracting force to the cutting blade.

As discussed above and further emphasized here,is merely an example which should not unduly limit the scope of the claims. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. According to some embodiments, different positional and/or torque limit profiles are possible depending upon the desired operation of a particular DOF, such as the cutting DOF more directly discussed in. In some examples, different torque limit values may be used in the extending and holding phases and/or in the retracting and garaging phases. In some examples, a more complex torque limit profile using ramps and/or the like are possible. In some examples, the torque limit may be variable based on the current position of the cutting blade.

is a simplified diagram of a methodfor performing a cutting operation according to some embodiments. One or more of the processes-of methodmay be implemented, at least in part, in the form of executable code stored on non-transient, tangible, machine readable media that when run by one or more processors (e.g., the processorin control unit) may cause the one or more processors to perform one or more of the processes-. In some embodiments, methodmay be performed by an application, such as control application. In some embodiments, methodmay be used to extend and retract a cutting blade, such as cutting blade, of a surgical instrument, such as surgical instrument. In some embodiments, the cutting operation of methodmay be performed according to positional profileand/or torque limit profile. In some embodiments, drive components such as those described inmay be used during the performance of methodto extend, retract, and/or maintain the cutting blade in an idle position.